This invention relates to an armrest assembly of a passenger seat that includes a manual mechanism by which a bed extension can be deployed to increase the bed size of a lie flat seat of the type found in first class cabins of passenger aircraft. The deployment of the bed extension is manually operated by the armrest movement. The bed extension cooperates with other bed elements that are deployed to convert a seating area into a sleeping area. Such bed elements collectively make into a bed of sufficient length to allow a passenger to recline into an essentially lie flat position. When the passenger is ready to resume sitting, the process is reversed, and the portion of the bed surface formed by the upper surface of the armrest reverts to use as an armrest.